1. Field
This invention relates to supplying borated water to commercial nuclear power plants.
2. Description of Related Art
Commercial nuclear power plant operators are exploring solutions to eliminate and/or mitigate damages caused by natural and/or man-made disasters, such as the tsunami that recently damaged the Fukushima nuclear power plant in Japan, including not only the reactors but many other supply systems permanently built on-site, with a substantial footprint. One system that is being examined is the water supply system. The boration of supply water is usually considered necessary to provide a neutron poison liquid to help maintain the reactor subcritical.
Use of boric acid solutions in nuclear reactors is taught early on, for example, by Panson in U.S. Pat. No. 4,764,337, which states that:                the use of boric acid for preventing or at least inhibiting carbon steel corrosion in the secondary water systems of nuclear steam generators has been known for some time. In particular, boric acid has been utilized to minimize the phenomena known as denting at the tube/-tube support plate interface in nuclear steam generators . . . . While boric acid alone has been found to be highly useful for inhibiting carbon steel corrosion of the type which results in denting, nuclear applications require a continuous search for improved systems and increased reliabilities. Diol boric acid compounds which are more strongly acidic than boric acid alone are known . . . . [There appears to be a] reaction between boric acid and diol compounds to activate boric acid by producing diol boric acid complexes which have more acidic characteristics than does boric acid itself. However there is no suggestion . . . that such diol boric acid complexes are capable of inhibiting corrosion. And even more so there is no disclosure that diol boric acid complexes might be useful for inhibiting carbon steel corrosion in nuclear steam generator applications.        
Importantly, it was later found that boric acid can be used as a moderator to suppress some neutron flux, as taught by U.S. Pat. Nos. 8,233,581 and 5,171,515 (Connor et al. and Panson et al., respectively). In another area, Brown et al., in U.S. Pat. No. 4,225,390 shows the level of complexity for boron control systems for nuclear power plants.
Boration supply systems currently in operation utilize a completely on-site, permanent batching tank of substantial size, requiring major auxiliaries to keep it “on-site useful,” to blend the desired concentration of boric acid and water to provide an appropriate solution prior to injection into the coolant water used within the reactor coolant system of a nuclear reactor.
The major disadvantage of current boration supply systems is that they require a very large permanent batching tank with attached components including a permanent motorized agitator and a heating system for mixing and maintaining relatively high concentrations of boric acid in solution. As such, current boration supply systems are a problem in that they require a large amount of space, that is, a large footprint, and a major amount of power. These requirements do not make the current boration supply systems readily transportable or mobile, and are permanently on-site. Thus, there is a need to mimic nuclear power plant boration systems with a system that provides a smaller in-place footprint, is easily transportable, and makes more efficient use of energy and resources during periods of time when the installed plant equipment is not operable or is not ready for use.